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Long‐wave infrared photodetectors play an indispensable role in a variety of fields such as science, technology, engineering, and medicine. However, to date, most conventional long‐wave infrared photodetectors need to be operated under low temperature to meet the performance requirements. This can lead to a series of problems such as large device volume and high operating cost. Therefore, it is urgent to explore novel long‐wave photosensitive materials. In recent years, the development of nanotechnology has opened a new door for long‐wave infrared photodetection. Herein, pulsed‐laser deposition is successfully applied to the preparation of Ge‐doped BiTe (GBT) thin films. Importantly, the corresponding GBT photodetector exhibits excellent long‐wave infrared photosensitivity. Specifically, upon 10.5 µm illumination, the responsivity, external quantum efficiency, and detectivity reach 1.41 mA W−1, 0.017%, and 1.96 × 106 Jones, respectively. Moreover, a fast response rate with the rise/decay time down to 42.5/41.1 µs is realized. On this basis, the GBT photodetector is used as the receiving unit for optical signals to achieve proof‐of‐concept long‐wave optical information transmission application. On the whole, this study provides a new material platform for long‐wave optoelectronic sensing. [ABSTRACT FROM AUTHOR]

As the fresh blood of 2D family, non‐layered 2D materials (2DNLMs) have demonstrated great potential in the application of next‐generation optoelectronic devices. However, stemming from the weak light absorption brought by atomically thin thickness and the interfacial recombination brought by surface dangling bonds, traditional 2DNLM photodetectors are always accompanied by limited performance. Herein, a structure that integrates Si nanopillar array and non‐layered 2D In2S3 to construct an ultrasensitive photodetector is designed. In particular, periodically Si nanopillars can act as Fabry–Pérot‐enhanced Mie resonators that can effectively control and enhance the light absorption of 2D In2S3. On the other hand, a vertical built‐in electric field is introduced in the In2S3 channel to capture photogenerated holes and leave electrons recycling in In2S3, obtaining a high photogain. Benefiting from these two mechanisms, this proposed photodetector presents a high responsivity of 4812 A W−1 and short rise/decay time of 5.2/4.0 ms at the wavelength of 405 nm. Especially, a high light on–off ratio greater than 106 and a record‐high detectivity of 5.4 × 1015 Jones are achieved, representing one of the most sensitive photodetectors based on 2D materials. This deliberate device design concept suggests an effective scheme to construct high‐performance 2DNLM optoelectronic devices. [ABSTRACT FROM AUTHOR]

MoS2-like layered 2D materials have attracted attention worldwide due to their intriguing material properties. In contrast, it is still a great challenge to prepare non-layered 2D materials that may provide unique electronic and optoelectronic properties compared to layered materials. As an emerging IIIA–VIA semiconductor, In2S3 shows great potential for application in optoelectronics. Herein, ultrathin non-layered In2S3 nanoflakes, with uniform thickness and lateral size reaching the sub-millimeter scale, are synthesized on mica substrates via a simple physical vapor epitaxy method. Then, a photodetector based on an In2S3/Si heterojunction is fabricated. Owing to the strong light–matter interactions of In2S3 and the built-in potential at the In2S3/Si interface, which accelerates the separation of photoexcited electron–hole pairs, the device exhibits a broadband sensitivity covering the visible to near-infrared region. The responsivity, detectivity and rise/decay time are 579.6 A W−1, 2 × 1011 Jones and 9/0.131 ms, respectively. These performance metrics are among the best values when compared with those of reported layered 2D materials/Si heterojunction photodetectors. Notably, the In2S3/Si photodetector suffers from negligible performance degradation even after 1050 cycles of operation or 6 months of exposure to air. These findings broaden the scope of 2D materials and highlight that In2S3 nanoflakes hold great potential for further optoelectronic applications. [ABSTRACT FROM AUTHOR]

Owing to their exciting electronic and optical attributes, layered materials have attracted great interest in the field of next-generation photodetectors. However, owing to their large dark current, low detectivity and small signal-to-noise ratio, the performance of photodetectors based merely on layered materials is unsatisfactory for use in weak signal detection. Integrating layered materials with mature silicon (Si) technology offers a feasible scenario to overcome these drawbacks. Herein, we report the facile synthesis of layered ZnIn2S4 nanosheets and the construction of a ZnIn2S4/Si heterostructure photodetector array for weak signal detection. Owing to the interfacial charge transfer, which significantly suppresses the dark current and accelerates the separation of the photoexcited electron–hole pairs, the fabricated ZnIn2S4/Si photodetector array presents an ultralow dark current (18 pA), superior signal-to-noise ratio (11 572), stable photoswitching and high detectivity (2 × 1012 Jones). Notably, the heterostructure device exhibits an outstanding weak signal detection capability, which has been successfully demonstrated using the detection of weak light sources including a cell phone screen, flashlight and lighter. These results demonstrate that the synergetic effect of layered materials and mature semiconductor technology shows great potential for application in next-generation optoelectronics. [ABSTRACT FROM AUTHOR]

Nanoelectronics is in urgent demand of exceptional device architecture with ultrathin thickness below 10 nm and dangling-bond-free surface to break through current physical bottleneck and achieve new record of integration level. The advance in 2D van der Waals materials endows scientists with new accessibility. This study reports an all-layered 2D Bi2Te3-SnSe-Bi2Te3 photodetector, and the broadband photoresponse of the device from ultraviolet (370 nm) to near-infrared (808 nm) is demonstrated. In addition, the optimized responsivity reaches 5.5 A W−1, with the corresponding eternal quantum efficiency of 1833% and detectivity of 6 × 1010 cm Hz1/2 W−1. These figures-of-merits are among the best values of the reported all-layered 2D photodetectors, which are several orders of magnitude higher than those of the previous SnSe photodetectors. The superior device performance is attributed to the synergy of highly conductive surface state of Bi2Te3 topological insulator, perfect band alignment between Bi2Te3 and SnSe as well as small interface potential fluctuation. Meanwhile, the all-layered 2D device is further constructed onto flexible mica substrate and its photoresponse is maintained roughly unchanged upon 60 bending cycles. The findings represent a fundamental scenario for advancement of the next generation high performance and high integration level flexible optoelectronics. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDs) manifest excellent phonon-limited mobility and strong light–matter interaction, which, however, conflict with the long response time and low responsivity of TMD-based photodetectors. The extreme susceptibility of TMDs' electronic qualities to the large density of unscreened disturbances from the SiO2 substrate accounts for such inconformity. Here, we evaluated the potential of WS2 for photodetectors by passivating SiO2 substrates with layered Bi2Te3, a representative three dimensional topological insulator. Comparative photoswitching measurements of the WS2/Bi2Te3 photodetector demonstrated its stable and broadband photoresponse from 370 to 1550 nm. Meanwhile, WS2 and Bi2Te3 allied a high responsivity of 30.7 A W−1, a pronounced detectivity of 2.3 × 1011 cm Hz1/2 W−1 as well as a short response time of 20 ms, which make the device stand out among previously reported WS2 photodetectors. In fact, the responsivity and detectivity are comparable to those of state-of-the-art commercial Si and Ge photodetectors (R∼ 0.5 to 0.85 A W−1, D*∼ 3 × 1011 to 3 × 1012 cm Hz1/2 W−1), suggesting its great potential for practical applications. In addition, we also established that the excellent device performance is attributed to the synergy of the passivation of the SiO2 substrate, efficient carrier separation at the WS2/Bi2Te3 heterointerface and excellent carrier transport along the time-reversal-symmetry protected surface channel of Bi2Te3. In summary, these findings suggest that the WS2/Bi2Te3 photodetector will launch a significant advance in next-generation photodetection. Moreover, the interface engineering strategy depicts a universal scenario for development of TMD devices in the future. [ABSTRACT FROM AUTHOR]